Pandemic, the first game in this duo, was released for Web browsers back in 2007. The object of the game was to infect a person with a disease you created, then manage the outbreak and evolve the disease to create the most worldwide damage. I agree that the game's subject is morbid, but the huge popularity of Pandemic showed that the actual content doesn't make it any less addictive.

At the beginning of last month, Pandemic 2.5 was released for iOS and quickly shot up the App Store's most-popular lists probably based on the Flash version's popularity. But at the end of May, a very similar game was released that might even be better than the original.

In testing these games, I infected most of the world with my various diseases, but never had one that destroyed all of humankind. Those who have played Pandemic in the past might guess that Madagascar was my downfall (it's a joke among Web gamers that Madagascar is always the one to close its shipyards at the first whiff of danger), but it was Iceland that put a stop to the deadly Parkerism.

Just like the Web version, touching a country brings up its stats, but zooming the map beyond what you see here is impossible.Photo by Screenshot by Jason Parker/CNET

Pandemic (99 cents) for iOS is a faithful re-creation of the popular Web-based game where the object is to play as a villain and infect our entire planet with an evolving disease. The game is obviously quite morbid, but it's also extremely addictive as you start with one infected person in a random location and try to spread a disease to every corner of the globe. You can choose from three skill levels at the beginning of the game, with the easiest setting for quick sessions allowing for more experimentation, and the hardest setting making it a real challenge to even get your disease off the ground.

Pandemic starts out with the simulation paused. Before getting started, your first step is to set up the kind of disease you're going to set loose on the world. You can choose from three disease types: Bacterial, Viral, or Parasitic. The three have different infection rates and give bonuses for specific attributes of the disease. With your type of disease selected, you get to give it a name before you get to the main map screen.

With the game still paused, your next step is to choose what your disease actually does to people using the disease menu in the lower right of the screen. Does your disease cause sneezing? Do people grow bumps on their skin? It's all up to you, but you can only develop your disease by spending eight EvoPoints in the beginning. You can also choose "supports" -- attributes that help with spreading your disease, such as better performance in cold weather or more resistance to drugs. Planning out the type of disease is one of the best parts of the game, and as you gain more points by spreading to other countries, you'll get more EvoPoints to make your disease even deadlier.

You get to pick from all the grisly symptoms you can think of, with descriptions for each when you touch one.Photo by Screenshot by Jason Parker/CNET

Pandemic makes for a fun simulation that requires plenty of strategy, but you are going to spend a significant amount of time waiting. A lot of the game is spent looking at growing infected numbers in different countries, and waiting for more points to cause your disease to evolve with. The worst part about this is when you know your disease is not going to spread farther (airports, shipyards, and borders are all already closed), but there's no way to simply speed to the ending to see your score. You have to wait for all the activity to die down, even if you have the simulation running at the fastest speed. Maybe a fast-forward-to-the-end button will be added in a later update, but it's hard to ding the game too hard for this oversight.

Another noticeable annoyance with Pandemic (particularly for iPad users) is that you can't view the action in landscape mode. While not a deal breaker, landscape mode seems to be the more natural way to play games on the iPad, and Pandemic would definitely benefit from the sideways orientation when viewing the large world map.

Still, if you can put aside the tragic nature of destroying every human being on the planet, Pandemic is definitely a great time-waster. There's a bit of a learning curve and you may have to wait during slow parts of the game, but even just watching the number of infected rise in various countries is very compelling. Those who want a slower-paced strategy game with lots of variables to play with (or feel nostalgia for the original Web-based game) should definitely check out the iOS version.

The Plague Inc. map is much brighter with easy-swipe controls. The game also displays informative windows at every turn.Photo by Screenshot by Jason Parker/CNET

Plague Inc. (99 cents) is a game that was obviously based on the same concepts as the classic Pandemic (was it copied or just improved upon?), but with Plague Inc. you get a much more intuitive interface and the flow of the game feels smoother. Plague Inc. is the same concept as Pandemic in most ways, but is a much better experience for those who have never played a game of this type before because there are tons of onscreen help windows and updates as your disease progresses.

Just like Pandemic, you start by creating the disease that will kill off human kind. In the beginning you only have the option for a viral infection, but once you finish your first game, you'll unlock a bacterial infection as your next challenge. Plague Inc. offers a total of seven infection types including even more-disturbing choices like Nano-Virus and Bio-Weapon variants you'll be able to unlock as you play. One notable difference from Pandemic is that you get to choose the country where your disease first takes hold. In other words, if you're worried about Madagascar's exceptionally safety-conscious shipyards, you could always start your disease there.

Once you've picked your location, the simulation begins. Just like Pandemic, you'll be able to watch as boats and planes make their daily trips around the globe (while you secretly hope an unwitting passenger is spreading your virus). You'll also be able to look at how many people are infected in each country, and -- unique to Plague Inc. -- you'll be able to view percentages and pie graphs showing how much your disease has spread. This is where Plague Inc. really shines; it doesn't make you just sit around waiting for things to happen. Along with constant updates onscreen, you also get balloons that pop up for different events -- like the infection of a new country -- which you can "pop" by touching them to get more DNA points.

The symptoms and transmission screens in Plague Inc. are much more intuitive, with more-advanced options that open up as you play.Photo by Screenshot by Jason Parker/CNET

In order for your disease to be successful, you'll need to make it evolve in the same way you do in Pandemic. But in Plague Inc. you get intuitive Transmission, Symptom, and Ability trees that make it easy to see how to evolve your disease for the biggest infection rate. You also have a World button where you can view the number of infected and the number of dead; progress on a cure for your disease; and a Data section that lets you view graphs for every aspect of your disease.

In the end, Plague Inc. uses a lot of the same concepts that made the original browser-based version of Pandemic so popular. But while Plague Inc. doesn't offer quite the number of ways to evolve your disease, it offers an interface that is extremely easy to understand making it a better choice for those new to the genre.